Case Folding

The element handler functions may get their element names
case-folded. Case-folding is defined
as "a process applied to a sequence of
characters, in which those identified as non-uppercase are
replaced by their uppercase equivalents". In other words, when
it comes to XML, case-folding simply means uppercasing.

By default, all the element names that are passed to the handler
functions are case-folded. This behaviour can be queried and
controlled per XML parser with the
xml_parser_get_option() and
xml_parser_set_option() functions,
respectively.